An Airflow Relief Valve is installed in a central vacuum system as near as possible to the power unit and provides an alternate pathway for airflow should the primary path become blocked. Often called a suction relief valve or motor protection valve and sold in a number of colors, this airflow regulation device uses an adjustable spring tensioned opening to allow airflow in to the vacuum system when it can not be pulled from the normal tubing system due to a blockage or clog. In the event an item was inadvertently vacuumed up that was so large or oddly shaped that it causes a clog in the vacuum line the airflow relief valve lets airflow in to "prevent motor damage".
Who should use an AFR valve?
An Airflow relief valve is only beneficial for those with thru-flow motor central vacuum power units. Thru-flow central vacuum motors use the same airflow for cleaning as they do for cooling the vacuum motor, or simply the air flows through the motor. If the thru-flow motor equipped central vacuum system becomes blocked then the vacuum motor is no longer cooling itself and will soon overheat. When a blockage occurs within a vacuum system equipped with an Airflow Relief device the valve will open up and allow cooling air to continue flowing into the motor. The AFR is the safety device that allows low-cost motors designed for portable vacuums to be used in central vacuums.
Who should NOT use an AFR valve?
Only those operating a built vacuum system using the thru-flow motor would benefit from a Airflow Relief valve. If your vacuum system uses a quality bypass motor then you do not need an AFR. Confirm with the manufacturer or dealer that your central vacuum power unit uses a thru-flow motor before installing an AFR valve. If your vacuum system is a Hide-A-Hose you should not install a AFR valve. Central vacuum systems using the traditional bypass motor do not require an airflow relief valve thanks to their superior design with two fan systems.
Bypass motors use one fan system to create suction (which bypasses the motor) and a separate cooling fan system for the motor which is not affected by a blockage in the vacuum intake line. Some power unit using thru-flow motors already have built in airflow relief valves or thermal sensors that shut the motor down when overheated. If your vacuum systems has a bypass motor you should also bypass purchasing an airflow relief valve. If you are considering purchasing a new vacuum which uses a thru-flow motor, first read our knowledge base articles on motor systems and consider finding a power unit with a bypass motor unit. Bypass motor systems do not need airflow relief valves, are much more efficient than thru-flow motors and often have a longer lifespan than thru-flow motors.
When AFR valves will NOT help.
If a blockage should occur in the line between the AFR and the power unit then the AFR valve will not help. If the blockage is internal in the vacuum system including a clogged filter, full bag or clogged cyclonic separation screen the AFR valve will not help with over heating of thru-flow motors. AFR valves can sometimes cause blockages by releasing suction from the vacuum system that was needed to pull a larger object through the tube system. Where the object would likely have traveled through the vacuum system without incident with full suction applied, an AFR valve will likely activate and cause the object to stop moving somewhere within the tube system and actually create a clog.
Before using an AFR valve confirm first you have a thru-flow motor vacuum power unit and that it is not already protected by a built-in AFR or an electronic thermal sensor.
Sold 1 each, black in color.
Does not include fittings that may be required to install.
Includes installation and setup instructions.